[PATCH 2/2] slub: Fix kmem_ptr_validate() for non-kernel pointers

From: Pekka Enberg
Date: Wed Apr 07 2010 - 12:34:40 EST

As suggested by Linus, fix up kmem_ptr_validate() to handle non-kernel pointers
more graciously. The patch changes kmem_ptr_validate() to use the newly
introduced kern_ptr_validate() helper to check that a pointer is a valid kernel
pointer before we attempt to convert it into a 'struct page'.

Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxxxxxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Matt Mackall <mpm@xxxxxxxxxxx>
Cc: Nick Piggin <npiggin@xxxxxxx>
Signed-off-by: Pekka Enberg <penberg@xxxxxxxxxxxxxx>
mm/slub.c | 3 +++
1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index b364844..7d6c8b1 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2386,6 +2386,9 @@ int kmem_ptr_validate(struct kmem_cache *s, const void *object)
struct page *page;

+ if (!kern_ptr_validate(object, s->size))
+ return 0;
page = get_object_page(object);

if (!page || s != page->slab)

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